Some 50 kilometres north of Beijing the Jundu and Taihang mountains rise forbidding and rugged from the flat, green countryside. High atop one of the peaks an eroded stone beacon echoes a time long ago when warnings of impending danger were sent by smoke rather than radar or telephone. Between outcroppings of stark, solid rock, ribbons of planted evergreen trees ring the mountain slopes like corduroy clothe.

The highway that leads north from the capital is broad and banked by green fields and orchards brimming with apples, pears and peaches. A convoy of People's Liberation Army flatbed trucks loaded with battle tanks roars by looking conspicuous and menacing. Beside the road, on a massive and decaying construction site, an abandoned, half-finished children's theme park stands testament to the fact that private enterprise doesn't always flourish in the new China

Further up the highway and from the maw of the Jundu Valley, the Great Wall of China rises into the mountains like a gash, it's pinnacle perched hundreds of metres above the ground like some Chinese Mount Olympus.

This is the Juyong Pass, "the most impregnable pass in the world", first settled more than 2700 years ago. Over millennia the pass and town were fortified and became part of the Great Wall, which itself took more than 900 years--and hundreds of thousands of lives--to complete. The history and scale of the Wall, even this "small' section of four kilometers, dwarves the tourists that swarm over its battlements.

The steps of the wall are sometimes narrow, at other times wide, flat or rolling or steeply sloped, worn by untold millions of footfalls. Like sand in a desert the stones absorb beads of sweat that drop from our foreheads.

And there is a lot of sweat. The temperature is somewhere in the mid-30s and it's a long haul to the top. At a distance the top looks deceptively close, and the going is easy enough at first but soon saps the will and energy of any but the fanatic and foolhardy

Yet how can one come all the way to China and to the Great Wall without climbing to the top? Mao once said: "He who does not climb the Great Wall is not a true man." But then, Mao said a lot of things. It's hard to imagine him, especially in his later years, heaving his well-fed body up these steps.

Besides, vast stretches of the 5,660 kilometre-long wall have decayed and aren't even suitable to climb, let alone open to tourists. Here is one of those "once in a lifetime" moments, and not even Dave's little blue flag could turn us back short of the summit.

At times the pace slows as crowds of climbers bottleneck around steep turns or stop for a rest at guard towers. Instead of detracting from the experience, the multitude of people adds a collective, almost spiritual flavor to the climb, as if we are pilgrims rather than tourists.

Voices call out in Russian, Korean, French, Spanish, Japanese, Arabic, and a dozen other dialects. A group of Egyptians asks a passerby to take their photo. On the ramparts of a lookout tower, a Venezuelan man plays a flute, sending a sweet, tender melody down over the wall and the valley below

In places where the mountain rock juts from the wall the stone has been worn smooth and charming by countless hands placed on them for balance, and perhaps reassurance. I will not falter, I am here, and I am blessed.

Most people rarely subject themselves to strenuous activity, though, and there comes a time when the body has had enough and starts to shuts down. Each step becomes more difficult than the last, and thoughts no longer stray but become focused on each labored movement. Some climbers have vomited from the strain, and surely others collapse and must be carried down. Emergency medical facilities are either well-hidden or, more likely, non-existent.

But thankfully, the summit of the Juyong Pass, the South Moon Tower, looms ahead, and the view from the tower's rooftop is all the more dramatic for the effort to get there. I've saved the last of my water bottle for this moment, and drain it with great satisfaction. My shirt is soaked, and pages of the notebook in my back pocket are transparent with sweat.

From the South Moon Tower the wall forks back down the mountain in two directions, one taking us back from whence we came, the other drifting towards the other guard towers and ramparts that make up the Juyong Pass.

What we've climbed today--1602 steps to the top, as counted by Mitch, a fellow Canadian on the tour--constitutes perhaps one fifth of the entire pass, but I can't imagine that anyone is up for more. We've climbed the Great Wall. Old Mao would be proud.